Patent GB-191108525-A (GB)
Title: Improvements in Governing Turbo-compressors in which Two Sources of Steam are Employed.
IPC: G05D13/00
Filed: 1911-04-05
Granted: 1911-08-31
Abstract: 8525. HarlÚ et Cie. April 6, 1910, [Convention date]. Regulating centrifugal fans. In blowing plant wherein the compressor is driven by mixed - pressure turbine, the high and low pressure admission valves are simultaneously controlled by the compressor output and by a speed-regulating governor, and the low-pressure supply is cut off when the pressure of the lowpressure supply falls below a predetermined limit. The turbine is supplied with low-pressure steam through a pipe a controlled by a valve d, and with high-pressure steam through a pipe b controlled by a valve e. The valve d is connected by a lever f to a vertically sliding rod g, while the valve e is connected by a lever k to a sleeve m slidably mounted upon the rod g and pressed against a shoulder thereon by a spring l, the lower end of which rests on a piston h slidably mounted upon the rod g. The lower part of the piston h is subjected to the discharge pressure of the compressor or to a pressure depending upon the output of the compressor. The upper end of the rod g passes freely through a piston p, but is provided at the top with a shoulder r, so that, while the rod can rise without affecting the position of the piston, the piston on rising raises the rod with it when it engages the shoulder r. The piston p is subjected above to a constant spring pressure, but is subjected below to an oil pressure varied by the action of a valve w controlled by the turbine governor z. The valves d, e are so adjusted that the valve d has no throttling effect until the valve e is fully closed. The operation of the device is as follows: When the discharge pressure of the compressor rises above the limit, the piston h rises and closes the valve e through the intermediary of the spring l, and at the same time lowers the valve d through the intermediary of the rod g, but sufficiently to throttle the supply of low-pressure steam. If further throttling is required, the piston h continues to rise, and with it the rod g, whereupon this rod slides through the sleeve m and completes the closure of the valve d. Should the discharge pressure of the compressor be only normal, but the speed of the turbine excessive, the action of the governor admits oil beneath the piston p, which rises and at the same time lifts the rod g, whereby the valves e, d, are closed as before. A dash-pot 16 prevents rapid fluctuations. The low-pressure supply pipe a is provided with an additional valve 1 connected to a piston 2, subjected above to the pressure of the supply and below to the pressure of a spring 3 combined with either the pressure of the supply or the condenser pressure, according to the position of a differential piston 6, which position is determined by the pressure of the supply. When the pressure of the supply is above a certain limit, the fluid pressure below the piston 2 is that of the condenser, and the pressure above is sufficient to overcome the pressure below, so that the valve 1 remains open, but, when the pressure of the supply falls, the fluid pressure below the piston is that of the supply, whereby the fluid pressures balance and the spring 3 closes the valve.